The study by Hurlstone and colleagues (Gut 2004;53:376–80) is commendable in raising the awareness of flat and depressed colonic neoplasia. However, I am surprised at the high rate of severe dysplasia reported in their study. Of their 170 lesions, 19% harboured high grade dysplasia. This high rate of severe dysplasia is particularly surprising as the study reported on diminutive colorectal lesions.

Large numbers of small adenomas develop as we grow older. According to autopsy studies, over 30% of the population over the age of 50 years have small adenomas.¹ With the use of dye spraying and magnification, these lesions can be found in up to 50% of asymptomatic patients attending for colonoscopy.² As only 5% of the population develop colorectal cancer, clearly the great majority of small adenomas never grow, advance, or turn cancerous. This conclusion is supported by studies reporting a lower than 1% risk of high grade dysplasia in small adenomas.^3–5

Further studies have reported on the risk of high grade dysplasia in adenomas of all sizes. In our own series from Leeds,⁶ high grade dysplasia was found in 9.5% of neoplastic lesions of all size ranges. Similarly, Tsuda and colleagues⁷ reporting on colorectal adenomas in Sweden found high …